Formation of droplets of shear‐thinningnon‐Newtonianfluids in a step‐emulsification microdevice

Abstract

AbstractIn this paper, the formation mechanism of droplets of shear‐thinning non‐Newtonian fluids in a step‐emulsification microdevice is studied experimentally, by using aqueous solutions of sodium carboxymethyl cellulose (CMC) as the dispersed phase and cyclohexane as the continuous phase. According to the evolution of the front‐end length of the dispersed thread over time, the droplet generation process is divided into three stages: the two‐dimensional expansion stage, the three‐dimensional rapid expansion stage, and the necking stage. The influence of the dispersed phase flow rateQdand CMC concentrationcon droplet formation is described. The results show that the addition of CMC in the aqueous solution increases the viscosity of the dispersed phase and slows down the evolution of the dispersed phase, thereby resulting in the increase of the droplet size. Finally, a droplet volume prediction model considering non‐Newtonian characteristics is proposed, and the formation of satellite droplets is analyzed.